The present invention relates to a dental handpiece for injecting an air-powder mixture together with water against teeth for dental treatment.
Dental handpieces are known which mix air and powders and inject the resulting mixture against tooth surface together with water for polishing or cleaning teeth.
For example, JP-10-179617-A discloses a dental tool of a handpiece type for injecting therapeutic agent. JP-10-286268-A discloses a dental handpiece for use in prophylaxis treatment of carious teeth by spraying powders mixed with air and water. This handpiece includes a powder container, an air flow line for supplying air into the container, a mixture transfer line for transferring a mixture of powders and air to a spray nozzle, a water supply line for transferring water to the spray nozzle for injection with the mixture against teeth, and tubes each connected to the air flow line or the mixture transfer line and projecting inside the container. The tips of the projecting tubes are perforated to form air outlet ports and mixture inlet ports, respectively.
In dental handpieces of this type, powders must be mixed with air at an appropriate concentration. For this purpose, the projecting tubes are arranged so that the air outlet ports and the mixture inlet ports are positioned substantially in the central region of the container.
This handpiece, however, is likely to be held in various positions during dental treatment by a dentist, so that the concentration of the air-powder mixture in the container may not always be at an appropriate concentration.
Further, when the air supply into the container is stopped with the air outlet ports being immersed in the powders, the powders flow back into the air flow line through the air outlet ports, to thereby cause clogging of the air flow line or decrease in the air supply.
On the other hand, the handpiece is connected to a hose for air and water supply into the air flow line and the water supply line. When the handpiece is moved in various positions during the treatment, the hose is often twisted or entangled to impair operability of the handpiece.
It is therefore an object of the present invention to provide a dental handpiece that provides improved mixing of powders and air in the container to give a mixture of an appropriate concentration.
It is another object of the present invention to provide a dental handpiece wherein the powder back flow into the air supply line is prevented irrespective of the position of the handpiece.
It is yet another object of the present invention to provide a dental handpiece which prevents twisting or entangling of the hose connected to the handpiece for air and water supply, during the operation of the handpiece.
It is still another object of the present invention to provide a dental handpiece having a nozzle that is hard to be clogged, and that enables concentrated injection of powders onto a particular location such as a gap between teeth.
According to the present invention, there is provided a dental handpiece for injecting an air-powder mixture and water against teeth for dental treatment, comprising:
a container for accommodating powders;
an air supply line for supplying air into said container to produce a mixture of said powders and said air in the container;
a mixture transfer line for transferring said mixture;
a water supply line for transferring water; and
an injection nozzle for injecting the mixture received from said mixture transfer line and the water received from said water supply line against a treatment site;
wherein said container has a curved inner surface for allowing whirl of air spatially in all directions in the container,
wherein said air supply line has a plurality of branched lines each extending in central part of the container to close proximity to the curved inner surface of the container, each of said branched lines having in its distal part a plurality of ports oriented to direct air flow therethrough along the curved inner surface of the container.
The dental handpiece of the present invention has a plurality of branched air supply lines in the container. Each branched line extends in the central part of the container to close proximity to the curved inner surface, and has in its distal part a plurality of ports oriented to direct the air flow along the curved inner surface of the container. With such structures, the air blown into the container effectively mixes with the powders to produce a mixture of a uniform concentration in the container. The mixture is then transferred through the mixture transfer line and injected through the nozzle against teeth to achieve ideal treatment effect.
The dental handpiece of the present invention may be provided with a check valve in the distal part of each branched line for preventing back flow of the powders into the branched lines through the ports. With such a check valve, back flow of the powders into the air supply line is advantageously prevented irrespective of the position or orientation of the handpiece.
The handpiece of the present invention may also be provided with a grip section between the container and the injection nozzle for an operator to grip. The grip section is preferably connected to the container rotatably and detachably. With such structure, a hose connected to the handpiece for supplying air and water to the air and water supply lines will not be twisted or entangled even when the handpiece is held in various positions during the treatment.
The injection nozzle of the present handpiece may be mounted rotatably with respect to the water supply line and the mixture transfer line. By rotatably disposing the injection nozzle, the operability of the handpiece is improved, and the directions of the mixture and the water injected through the nozzle may be adjusted easily for achieving the optimum treatment effect.
The injection nozzle of the present handpiece may be provided with a mixture transfer line having a mixture injection outlet, and a water transfer line having a water injection outlet, so that the air-powder mixture and the water are transferred and injected separately through the injection nozzle. By providing separate transferring lines and injection outlets for the mixture and the water, clogging of the injection nozzle is advantageously prevented.
The mixture injection outlet may be formed so as to inject the air-powder mixture in a flat stream, and more specifically, the outlet may be formed in the form of a slot. With such an injection outlet generating a flat stream of the mixture, the mixture may be injected easily against every hole and corner of the teeth including gaps between teeth.
The water injection outlet may be arranged to surround the mixture injection outlet. This arrangement further enhances mixing of the water with the air-powder mixture without causing clogging in the injection nozzle.